Although the present invention has general applicability to any mechanical system in which a solid material is dissolved in a liquid and the liquid is dispensed from a container, the invention will be discussed in detail as it concerns a solid halogen donor delivery system.
The formation of slimes by microorganisms is encountered in both naturally occurring bodies of water such as ponds, lakes, lagoons and streams as well as in confined aqueous systems such as cooling towers, boilers, air washer systems, pulp and paper mills and the like. All possess conditions which are conducive to the growth and reproduction of slime-forming microorganisms. In both once-through and recirculating cooling systems, for example, which employ large quantities of water as a cooling medium, the formation of slime by microorganisms is an extensive and constant problem.
Airborne organisms are readily entrained in the water from cooling towers and find this warm medium an ideal environment for growth and multiplication. Aerobic and heliotropic organisms colonize and grow in such areas as the tower sump and the piping and passages of the cooling system. The slime formation not only aids in the deterioration of the tower structure in the case of wooden towers, but also promotes corrosion when it deposits on metal surfaces. Slime carried through the cooling system plugs and fouls lines, valves, strainers, etc., and deposits on heat exchange surfaces. In the latter case, the impedance of heat transfer can greatly reduce the efficiency of the cooling system.
In pulp and paper mill systems, slime formed by microorganisms is commonly encountered and causes fouling, plugging or corrosion of the system resulting in work stoppages and the loss of production time. Slime is also responsible for unsightly blemishes in the final product, which result in rejects and wasted output.
The previously discussed problems have resulted in the extensive utilization of bactericides in aqueous systems to control bacteria. One treatment for microorganism control is to add halogen to the affected aqueous system. Gaseous halogens can be added to the system, however gaseous systems are subject to halogen gas leaks which are hazardous to personnel. An alternative to using gaseous halogen is to use solid, halogen donor chemicals that release active halogen (usually bromine or chlorine) when dissolved in water. After release, the halogen reaction on the target microorganisms is similar to that from other halogen sources. Typical solid halogen donors include 1-bromo-3-chloro-5,5-dimethylhydantoin, 1,3-dichloro-5,5, dimethylhydantoin, and sodium dichloroisocyanurate. These donor chemicals do not release the active halogen all at once, but make it slowly available; therefore, they may be considered "controlled release" oxidizing agents. These donors are widely used because of the simplicity, low capital cost, and low installation cost of the feed systems. In addition, because they are solids, they reduce the handling hazards associated with gases (escapement) and liquids (spills).
Solid halogen donor chemicals are usually stored in and dispensed from polymeric containers which are delivered to the treatment site. A typical solid halogen donor delivery system is the Ultra-Brom.RTM. 36 system available commercially from Betz Industrial. The polymeric containers have influent water sources near the bottoms of the containers which supply water into the container. The water dissolves the solid halogen donor material and is dispensed from the container into the system to be treated. Typical tanks are re-filled through a resealable orifice and have a side mounted dispensing port through which the water and halogen are dispensed.
Although this arrangement is safer than gaseous halogen systems, this arrangement also has several disadvantages. If the container is filled with a solid halogen donor material to a level higher than the dispensing port, water supplied into the container can wet but not immerse the solid halogen donor material. If wet but not immersed, the solid halogen donor material can release gaseous halogen and heat, which increases the pressure within the tank and associated piping. If a pipe or pipe fitting bursts due to the increased pressure, halogen gas can escape the container causing a toxic hazard to nearby personnel. In addition, because solid halogen donor materials dissolve slowly, it is necessary to utilize a strainer or sieve diffuser to filter out undissolved particulates from the halogenated water stream dispensed from the container. The diffuser is subject to clogging and wear due to the flow of particulates within the container. Mounting a diffuser to side mounted container discharge ports makes the diffuser difficult to remove for inspection and replacement. A side mounted diffuser 101 attached to side mounted port 100 are shown in dashed lines in FIG. 1 to illustrate the problem. As shown in FIG. 1, the only way to remove diffuser 101 is to reach inside tank 11 through orifice 13 to access diffuser 101.
A need therefore exists for a liquid dispensing apparatus which provides flooding of solid halogen donor materials within a container regardless of the donor material height within the container. A need also exists for a liquid dispenser apparatus which provides easy access to the diffuser so inspection and replacement of the diffuser is facilitated.
Accordingly, it is an object of the present invention to provide a liquid dispensing apparatus for attachment to a container wherein solid material within the container is always flooded regardless of the amount of solid donor material within the container. It is also an object of the present invention to provide a liquid dispensing apparatus in which a liquid diffuser is accessible for removal, inspection and replacement.